ES2265773A1 - Mineral product for the technological improvement of aerobic biological treatments and corresponding use thereof - Google Patents

Abstract

Mineral product for the technological improvement of waste-water purification by means of aerobic biological treatments and use. Said mineral product is characterised by containing clays and mineral carbonates.

Description

Mineral product for the technological improvement of Aerobic biological treatments and use.

Technical Field of the Invention

The present invention fits within the field of wastewater treatment and purification by aerobic biological treatments. More specifically, it refers to a mineral product that contains clays and mineral carbonates, especially useful for the technological improvement of said processes

State of the art prior to the invention

Wastewater treatment constitutes one of the fields that have developed the most in recent years years. The imposition of increasingly restrictive laws by part of the different Administrations, along with a greater awareness by society, has increased the efforts in the search for adequate treatment systems and depuration.

The use of biological treatments is gone imposing in recent years as a way to improve the quality of sewage All systems are based on action natural bacteria, however there is a large number of variations well known and described in the art. Certainly the best known and used version corresponds to the so-called system of active sludge. Among the other possibilities, it stands out particularly the use of SBR technology (Sequencing Batch Reactor), characterized in that all processes take place in a single tank

The use of fixed or mobile fillings as a form of improve the efficiency and design of aerobic biological systems is well known. Together with the plastic fillings, the use of fixed or mobile bed of mineral products. Among them the use of activated carbon powder and of zeolites (natural and modified). The advantages associated with the use of both products can be summed up in greater stability of the system, as a result of better sludge decantation biological, an improvement in the nitrification capacity of the system, and elimination of non-biodegradable contamination.

Clays have been proposed for use in water purification treatments. This has been due to some properties of said materials, such as their high porosity, its high specific surface area and its high capacity of cationic exchange, which give them their characteristic high absorption and adsorption capacity.

Clays have been studied both naturally and modified. With these modifications we have sought to vary some of the characteristics of the clay. Thus, the treatment of clays with inorganic acids causes the cleaning of the material and an increase in the porosity and the specific surface. An increase in porosity is also achieved with the heat treatment of the clays. The objective sought has been the preparation of specific products for specific problems. As an example, the treatment of clays with certain organic reagents gives them hydrophobic characteristics, used for the selective removal of organic pollutants.
cos.

More specifically, the clays have been Proposals for use in biological clearance treatments, good aerobic good anaerobic, acting as porous support that allows the growth and fixation of the bacteria that act in The debugging process. In comparison with the other materials named above that serve as support (active carbon, ceramic materials, plastics), it has been proposed that traces of elements such as copper, zinc, iron, magnesium and other fixed Electrostatically in clays serve as nutrients to bacteria

Some examples illustrate the use of clays in wastewater treatment and purification processes through biological treatments:

- US Patent 3,935,067: describes the use of sodium bentonite as a support for a bacterial culture that uses a bacteria growth promoter.

- Patent FR 2,551,048 A1: describes the use of attapulgite and sepiolite in the purification of tank effluents from alcoholic fermentation containing type bacteria Phototrophic

- Patent ES 2.005.754: describes the treatment of wastewater in the presence of a clay mineral filler in anaerobic digesters of expanded or fluidized bed.

Said fill can be selected from sepiolite, smectite, vermiculite, kaolinite, chlorite, haloisite, ilita or paligorskita.

- WO 94/20425: describes the use of talc, kaolin or mica in a debugging process using the system activated sludge.

- US Patent 5,643,453: describes the use of kaolin as a support for bacteria in biological treatments aerobics

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- EP 0834473 A1: describes an activator biological for septic tanks constituted by clays together with cations so that fixation and activity of the natural enzymes of the process.

- US Patent 6,503,740: describes the use of organically modified clays as a support for bacteria in the decomposition of chemical contaminants. The proposed clays They are smectites, sepiolite, attapulgite, kaolinite, among others.

The object of the present invention relates to a mineral product for wastewater treatment by aerobic biological treatments, containing said mineral product clays and mineral carbonates. Some examples representative of systems containing mineral carbonates in its composition in the treatment and / or purification of water residuals by aerobic biological treatments are cited to continuation:

- Patent 3,440,619: proposes the use of calcium carbonate, magnesium carbonate, limestone or dolomite as solid support of bacteria.

- Patent 3,501,563: describes the use of limestone or dolomite to control the pH at an appropriate value for the biological treatment of wastewater in a process Combined mechanical, chemical and biological purification. The adition of limestone or dolomite is done in the process physiochemical.

- Patent ES 2,087,833: describes an activator biological chemical whose composition includes calcium carbonate and magnesium carbonate, which provide enough calcium and magnesium necessary for the proper development of microorganisms

- JP Patent 2004167471: describes a material for water treatments where bacteria can be fixed. That material consists of sulfur powder and a carbonate of a alkaline earth.

The applicant has now discovered a product mineral containing clays and mineral carbonates, which constitutes the object of the present invention and that as far as he has been able to investigate has not been used to date for the purpose proposed here.

Detailed description of the invention

The present invention relates to a product mineral that contains:

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45 a 95% by weight of clays, and;

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between 4 and 55% by weight of mineral carbonates,

and said mineral product has been modified through a treatment selected from:

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a heat treatment at a temperature between 20 and 1200 ° C., For a time between 10 seconds and 24 hours, and / or;

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a treatment with a chemical selected from an acid inorganic, an organic acid, one or more acid salts inorganic and one or more salts of organic acids.

In more detail, the present invention is refers to a mineral product that contains clays and carbonates minerals, said clays being selected from sepiolite, paligorskite, smectites, ilite, and mixtures thereof, as products minerals useful in the treatment and treatment of wastewater through aerobic biological purification treatments.

Both clays and mineral carbonates present in the mineral product that is the subject of the invention, are active part in the usefulness of the mineral product for the treatment and purification of contaminated wastewater through aerobic biological treatments.

In turn, the clays are selected from sepiolite, paligorskite, smectites, ilite and mixtures thereof, in following percentages:

% (p / p) - sepiolite and / or paligorskita: 5-80 - esmecitas: 5-40 - ilita: 0-30

with respect to the total weight of the composition.

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The smectites are selected from the group formed by: montmorillonite, beidellite, hectorite, nontronite, saponite, sauconite, estevensite, and mixtures thereof.

The mineral carbonates they form start from mineral product object of invention are selected from calcite (CaCO3), magnesite (MgCO3), dolomite (CaMg (CO 3) 2), siderite (FeCO 3) and its mixtures

In addition, the mineral product subject to invention may optionally contain up to 20% (w / w) of others minerals selected from the group consisting of: feldspars, plagioclase, micas, quartz, kaolinite, talc, chlorite, vermiculite, haloisite and mixtures thereof.

Mineral carbonates are materials well known to man. Due to its historical importance and industrial applications, calcium carbonate (CaCO 3; calcite or limestone), magnesium carbonate (MgCO 3; magnesite) and double calcium and magnesium carbonate (ideal formula) stand out among them MgCa (CO 3) 2;
dolomite).

Minerallogically, a specific group of phyllosilicates is called clays. The structure of these phyllosilicates is based on the stacking of oxygen and hydroxyl ion planes. The tetrahedral groups of SiO4 {4-} are joined by sharing three of their four oxygens with other neighbors forming layers of infinite extension and formula Si_2O5 {2-}, which constitute the fundamental unit of the phyllosilicates. The tetrahedral silicon may be partly substituted by Al 3+ or Fe 3+. These tetrahedral layers are joined to other octahedral ones of gibbsite or brucite type. The plane of union between both layers is formed by the apical oxygens not shared by the SiO4-4 tetrahedra and by the OH - groups of the layer
octahedral.

A similar bond can occur on the surface opposite of the octahedral layer. Thus, phyllosilicates can be formed well by two layers, tetrahedral plus octahedral, denominating then 1: 1 phyllosilicates, either by three layers, a octahedral and two tetrahedral, then called phyllosilicates 2: 1. The unit formed by the union of these two or three layers, is called foil. If all the octahedral holes are occupied, the foil is called trioctahedral. If only two thirds are occupied of these positions and the rest is vacant, it is called dioctahedral

The group of serpentine-canditas are 1: 1 philosophies. How 2: 1 phyllosilicates groups are included talc-pyrophyllite, smectites, vermiculites, ilites, Micas and chlorite.

They also fall within the term clays to the minerals of the hormite group, formed by minerals of the paligorskita-sepiolite family. TO unlike the rest of the phyllosilicates, which are laminar, they have a fibrous habit, since the basal layer of oxygen is continuous, but apical oxygen undergoes a periodic inversion every six tetrahedra (sepiolite) or every four tetrahedra (paligorskita / attapulgita). This investment causes the formation of channels in which large molecules can be accommodated.

The mineral product object of the invention it presents a mineralogical composition that contains between 45 and a 95% of clays and between 4 and 55% of mineral carbonates. These clays are a mixture of sepiolite and paligorskite (between 5 and 75%), smectites (between 5 and 40%) and ilite (between 0 and 30%). The mineral product can present up to a 20% of other minerals, which can be said minerals, feldspars, plagioclase, micas, quartz, kaolinite, talc, chlorite, vermiculite, haloisite and mixtures The percentages are always referred to Total composition.

To obtain the mineral product you can selectively exploit a deposit, extracting a rock clay containing the ingredients that are part of the mineral product in the percentages indicated. This clayey rock It is extracted from the reservoir with a humidity greater than 30%. Subsequently it is subjected to processes of collection, grinding, drying and granulated, being possible to use in these processes any of the systems commonly used in industry.

It is also the object of the invention to obtain mineral product described through the mixture of several components, containing each of them, one or more of the ingredients that are part of the mineral product. Said mixture it can be performed by any of the methods well known in the industry, being able to be subsequently subjected to processes of ground, dried and granulated.

The mineral product object of the invention is preferably presents as a granular porous product with grain size less than 5 mm, preferably less than 0.6 mm, preferably less than 150 µm, preferably less than 10 \ mum.

Previously, various processes have been commented of modifying clays such as heat treatments, acid activation, or addition of organic reagents. Since these processes are known and usually used in the industry are It also considers object of invention a mineral product for treatment and purification of contaminated wastewater by aerobic biological treatments, said mineral product being result of the modification by any of said treatments of the mineral product object of the present invention.

In accordance with the foregoing, this invention also encompasses a mineral product as defined previously modified by a heat treatment process. Said heat treatment process is carried out at a temperature between 20 and 1200 ° C, during a period of Time between 10 seconds and 24 hours. Behind the heat treatment, the mineral product can be subjected to a granulation process until the desired grain size is achieved, indicated above.

Also, the present invention also encompasses a mineral product that contains clays and mineral carbonates as defined above modified by a process of treatment with organic and / or inorganic chemicals. In particular, said modification is carried out by mineral product treatment with organic acids and / or Inorganic and its salts.

The procedure is also the subject of the invention. of use of the mineral products described in the treatment and wastewater treatment through biological treatments aerobics

It is also considered an object of invention, the use of the mineral products described in purification processes aerobic biological in combination with pH correction agents, flocculants, coagulants, bleaching agents and mixtures thereof. The product mineral can be present in any of the possible phases of those recorded in the aerobic biological process in which they are found present the bacteria responsible for the purifying activity of the process. The mineral product can be used both in systems of fixed bed as in fluid bed systems.

For use in fluid bed systems, the mineral product can be added well in its solid form well in suspension form. Said suspension can be obtained by mixing the mineral product object of the main patent with water or with The spill to be treated. The amount of mineral product to be used is between 0.001% and 50%, preferably between 0.001% and 20%, preferably between 0.001% and 10%, and more preferably between 0.001% and 1%, always in dry matter regarding one liter of wastewater to be treated. The addition of Mineral product object of the invention can be carried out in any of the phases as long as you contact the sludge of the biological process. Especially preferred are the addition during the aeration process of the mixed liquor or the addition on the active sludge recirculated from the tank Decanting to the aeration tank, in a sludge type process assets or similar.

The addition of the mineral product subject to invention produces the increase in the number of microorganisms responsible for the purification of the discharge present in the reactor biological. That increase in the amount of biological sludge has been also seen accompanied by a decrease in the volume occupied by said sludge and with an improvement in its decantation speed. These observations describe the mineral product subject to invention as an effective biological activator in processes of aerobic clearance, increasing the purification capacity of existing biological reactors. Its use also allows design of aerobic biological reactors of smaller volume, but that maintain their purification capacity and do not cause a greater volume of excess sludge that must be treated later.

Also, by using the mineral product for purification of water object of the invention a decrease in the value of the Mud Volume Index (IVF), included, said decrease, in a range between 15% and 85%.

Likewise, through the use of the mineral product for purification of water object of the invention a improvement in one or more of the water purification parameters treated residual, said parameters may be any of the considered to evaluate the quality of the purification obtained, highlighting in a non-limiting manner the following: pH, Demand Oxygen Chemistry, Biological Oxygen Demand, Solids in Suspension, Total Suspension Solids, Total Nitrogen Kjeldahl (NTK), ammoniacal nitrogen, nitrogen in the form of nitrates and / or nitrites, phosphorus concentration, element concentration Metallic, concentration of Oils and Fats, V 30, Conductivity, Turbidity, smell and color.

Embodiments of the invention

The valuation of the utility of the product mineral object of invention in the purification by treatments aerobic biological contaminated sewage was carried to conducted by comparative analysis of the parameters well known in the industry that characterize water quality residual:

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pH

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Chemical Oxygen Demand (COD; mg / l)

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Biological Oxygen Demand (BOD; mg / l)

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Total Nitrogen Kjeldahl (NTK; mg / l)

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Conductivity (µS / cm)

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Turbidity (NTU)

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Suspended Solids (SS; mg / l)

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Oils and Fats (mg / l)

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V 30 (ml)

Additionally, the main ones were considered parameters that characterize biological purification systems aerobic

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Solids in reactor suspension biological (SSLM; mg / l)

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Volatile Suspended Solids biological reactor (SSVLM; mg / l). Determine the concentration of microorganisms inside the biological reactor.

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Load Mass (C m; kg COD / kg SSVLM x day). Mark the relationship existing between the feed to the biological reactor and the existing microorganisms in it and is defined by the following formula:

C_ {m} = \ frac {COD_ {e} \ x \ Q_ {e}} {SSVLM \ x \ V_ {r}}

where COD_ {e} is the COD input to the reactor, Q_ {e} is the input flow and V_ {r} is the volume of the biological reactor.

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Index Mud Volumetric (IVF, ml / g). Represents the volume occupied by a gram of biological mud.

The present invention is illustrated by the Next Example, which should not be considered as limiting at all of its reach.

Example

The example illustrates the use of the mineral product object of the invention in an aerobic biological purification process of wastewater from the industry of slaughterhouses

Piloting was carried out using technology SBR (Sequencing Batch Reactor). This technology is chosen at consider that the results obtained in the piloting are more easily extrapolated to an industrial plant. Likewise all The results obtained in this technology can be subsequently extrapolated to conventional treatments with clarification by decantation (active sludge).

Two pilot reactors were prepared. First of them (Reactor 1) was taken as a blank test or standard. He second (Reactor 2) was used to add a daily composition according to the invention. Each of them works with a day-long aerated homogenization raft of hydraulic retention

The wastewater studied came from a slaughterhouse. 5 samples are taken at the plant three times per week The COD values of the discharge show great variation due to the different natures of the sacrificed species In the slaughterhouse. Its value ranges between 1800 and 10000 mg / l

For the start-up of both reactors, inoculated with biomass from a water purifier urban waste This type of biomass was chosen by criteria Biological and proximity. This mud had values of SSLM and SSLVM of 2400 mg / l and 2040 mg / l respectively. Load Starter mass of both reactors was 0.25 kg DQOIkg SSVLM

After one month, the values of SSLM (3500 mg / l) and SSVLM (2800 mg / l) of both reactors show that the sludge Urban biological has adapted to the spill to be treated. From At this time, a composition according to the invention directly in Reactor 2 in a dose of 2 g / l.

The analytical results of the purified discharge for both reactors they show hardly any differences between them. The Addition of the mineral product object of the invention does not influence pH values (which is maintained in an optimal range of operation) or conductivity. COD removal with both reactors is of the order of 96%, with values at many times, less than 100 mg / l. Something similar can be commented on the Concentration of Oils and Fats or on the NTK value. Both of them reactors get purification with effluents that meet the most restrictive laws in this regard.

The most significant difference between the two reactors is given by the values of SSLM, SSVLM and C_ {m}. In Table 1 shows the ranges for these parameters in both reactors during the pilot period.

TABLE 1

Reactor one Reactor 2 SSLM (mg / l) 3500-5000 8000-10000 SSVLM (mg / l) 3000-4500 5000-8000 C_ {m} (kg COD / kg SSVLM x day) 0.20 0.11

The big difference in SSLM values comes marked by the inorganic nature of the mineral product subject to the invention, which is added in Reactor 2 in a dose of 2 g / l. The comparison between SSVLM makes the difference between the solids concentrations that really intervene in the process of purification of treated waste. The concentration in the Reactor 2, where the mineral product object of the invention is added, is 1.6 to 1.8 times higher than in Reactor 1.

As mentioned, Reactor 1 is capable of produce a perfect purification of the treated discharge, indicating that The C_m value of 0.20 kg COD / kg SSVLM per day is adequate. From logical form, Reactor 2, where the addition of the mineral product object of invention, could purify the spill treated if it operated with the same pour value of C_ {m}. Based on the definition of C_ {m}, and considering the value of SSVLM in Reactor 2, it is verified that the addition object of invention to an aerobic biological reactor, allows to purify well adequately higher pollutant loads, well the design of new reactors with a smaller volume. Specifically yes we designed Reactor 2 to work with that mass load of 0.2 kg COD / kg SSVLM, we would obtain that the volume of Reactor 2 would be 40% lower than the volume of Reactor 1.

That design would also be endorsed by the different behavior observed in both reactors in the decantation of the sludge produced, as reflected in the IVF values of each of the reactors (table 2).

TABLE 2

Reactor one Reactor 2 IVF (ml / g) 209 82

The reduction in the value of 60% is observed. This is also achieved with an SSLM value of double for the Reactor 2, in which the mineral product object of the invention.

The volume occupied by said sludge in the Reactor 2 is approximately 40% lower than the sludge obtained in Reactor 1. The use of a mineral product according to the invention would allow to design a reactor with smaller volume without This is why there is a greater amount of biological sludge in excess, maintaining the same capacity of purification of the spill treaty.

Claims (19)

1. A mineral product for the technological improvement of aerobic biological treatments characterized in that it comprises:

-

45 a 95% by weight of clays; Y,

-

between 4 and 55% by weight of mineral carbonates,

and said mineral product has been modified through a treatment selected from:

-

a heat treatment at a temperature between 20 and 1200 ° C, for a time between 10 seconds and 24 hours, I;

-

a treatment with a chemical selected from an acid inorganic, an organic acid, one or more salts of inorganic acids  and one or more salts of organic acids.

2. A mineral product according to claim 1, characterized in that said clays are sepiolite and / or paligorskite. 3. A mineral product according to one of claims 1 or 2, characterized in that said clays are selected from the group consisting of sepiolite, paligorskite, smectites, ilite and mixtures thereof. 4. A mineral product according to claim 3, characterized in that said clays are presented in the following percentages: % (p / p) - sepiolite and / or paligorskita: 5-80 - smectites: 5-40 - ilita: 0-30 with respect to the total weight of the composition. 5. A mineral product according to claim 1, characterized in that said smectites are selected from the group consisting of montmorillonite, beidellite, hectorite, nontronite, saponite, sauconite, estevensite and mixtures thereof. A mineral product according to one of claims 1 to 5, characterized in that said mineral carbonates are selected from the group consisting of CaCO 3, MgCO 3, CaMg (CO 3) 2, FeCO 3 } and their mixtures. 7. A mineral product according to any one of the preceding claims, characterized in that it additionally includes up to 20% by weight of minerals selected from the group consisting of feldspar, plagioclase, micas, quartz, kaolinite, talc, chlorite, vermiculite, haloisite and mixtures thereof , always with respect to the total weight of the composition. 8. A mineral product according to any one of the preceding claims characterized in that it is presented as a granular porous product with a grain size of less than 5 mm, preferably less than 0.6 mm, preferably less than 150 µm, preferably less than 10 µm. 9. Use of a mineral product defined in any of claims 1 to 8 in treatments of wastewater treatment through biological treatments, good aerobic good anaerobic. 10. Use according to claim 9, characterized in that the treatment is carried out by aerobic fixed bed biological treatment systems. 11. Use according to claim 9, characterized in that the treatment is carried out by aerobic biological systems of mobile bed. 12. Use according to claim 9, characterized in that the treatment is carried out by means of a system corresponding to the active sludge technology.

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13. Use according to claim 9, characterized in that said system corresponds to the SBR (Sequencing Batch Reactor) technology. 14. Use according to one of claims 9 to 13, characterized in that pH correction agents, flocculants, coagulants, bleaching agents and mixtures thereof are additionally used. 15. Use according to one of claims 9 to 14, characterized in that the amount of mineral product is between 0.001 and 50% in dry matter with respect to one liter of the wastewater to be treated. 16. Use according to one of claims 9 to 15, characterized in that the mineral product is added in solid form. 17. Use according to one of claims 9 to 16, characterized in that the mineral product is added in the form of a liquid suspension. 18. Use according to any of claims 9 to 17, characterized in that there is a decrease in the value of the Mud Volume Index (IVF), in a range between 15% and 85%. 19. Use according to any of claims 9 to 17, characterized in that there is an improvement in one or more of the treated wastewater treatment parameters, said parameters being any of those considered to evaluate the quality of the treatment obtained, highlighting in a non-limiting manner the following: pH, Chemical Oxygen Demand, Biological Oxygen Demand, Suspended Solids, Total Suspended Solids, Kjeldahl Total Nitrogen (NTK), ammoniacal nitrogen, nitrate and / or nitrate nitrogen, concentration of phosphorus, concentration of metallic elements, concentration of Oils and Fats, V 30, Conductivity, Turbidity, odor and color.